During wash and rinse cycles, dishwasher appliances generally circulate a fluid through a wash chamber over articles, such as pots, pans, silverware, etc. The fluid can be, e.g., various combinations of water and detergent during the wash cycle, or water (which may include additives) during the rinse cycle. Typically, the fluid is circulated during a given cycle using a pump. Fluid is collected at or near the bottom of the wash chamber and pumped back into the wash chamber through, e.g., nozzles in spray arms and other openings that direct the fluid against the articles to be cleaned or rinsed.
Depending upon the level of soil on the articles, fluids used during wash and rinse cycles can become contaminated with soils in the form of debris or particles that are carried with the fluid. In order to protect the pump and recirculate the fluid through the wash chamber, it is beneficial to filter the fluid so that relatively clean fluid is applied to the articles in the wash chamber and soils are removed or reduced from the fluid supplied to the pump.
Accordingly, dishwasher appliances are generally provided with a filter assembly to trap at least certain of the soils carried with the wash fluid. Such filter assemblies generally include a course filter and a fine filter in a parallel flow configuration. For example, during a wash cycle a portion of the recirculated wash fluid may pass through the course filter and a portion of the recirculated wash fluid may pass through the fine filter. Through the course of the wash cycle, it is expected that substantially all of the wash fluid will pass through the fine filter, such that eventually all soils larger than a maximum predetermined size (i.e, a size of soils filtered by the fine filter) are removed from the wash fluid.
With such a configuration, the components of the dishwasher appliance must be selected to accommodate soils that are larger than the predetermined size and may pass through the course filter. However, such a construction may lead to inefficiencies and/or longer wash cycle periods. Therefore, a filter assembly for a dishwasher appliance capable of reducing the maximum predetermined size of particles that pass through circulation components of the dishwasher appliance would be useful. More particularly, a filter assembly for a dishwasher appliance capable of filtering all of the wash fluid to be recirculated through a fine filter would be especially beneficial.